The present invention relates to a display panel and, more particularly, to an organic light-emitting diode (OLED) display panel.
Organic light-emitting diode (OLED) display panels, also referred to as “organic electroluminescent display panels, are new flat panel displays having a promising application due to advantages of simple production, low cost, low power consumption, high luminance, wide operating temperature range, high speed response, ease of color display, large display area, easy match with integrated circuit drivers, and ease of flexible display.
With reference to FIG. 5, an OLED display panel generally includes a substrate 1, a semiconductor layer 2 (also referred to as “ITO layer”) on the substrate 1, an electrode layer 6 on the semiconductor layer 2, and a structure layer between the semiconductor layer 2 and the electrode layer 6. The semiconductor layer 2 is electrically connected to a positive pole to form an anode. The electrode layer 6 is electrically connected to a negative pole to form a cathode. The structure layer includes a hole transporting layer (HTL) 3 connected to the semiconductor layer 2, an electron transporting layer (ETL) 5 connected to the electrode layer 6, and an emissive layer (EL) between the hole transporting layer 3 and the electron transporting layer 5. When a suitable voltage is applied to the semiconductor layer 2 and the electrode layer 6, electron holes generated in the anode combine with electrons generated in the cathode to emit photons. Red, green, and blue (the three basic colors) lights can be generated according to different formulations.
Since the electrode layer 6 is generally made of metal and, thus, has a high reflectivity, an OLED display panel has poor readability due to reflection of light when used in a bright, outdoor environment.
In this industry, a circular polarizer (consists of a linear polarizer and a quarter wave plate) is used to reduce the reflectance of the ambient light. However, the circular polarizer is expensive. Furthermore, the ambient light is not a monochromatic light. Furthermore, in addition to passing through the linear polarizer and the quarter wave plate, the ambient light also passes through the material and the middle structure of the OLED such that a portion of purified linearly polarized light turns into elliptically polarized light, and a large portion of light is, thus, reflected, failing to provide a complete blocking effect. In a bright environment, the luminance of the OLED must be increased to improve the readability at the cost of an increase in the power consumption. Furthermore, more than 50% of the light output of the OLED is lost after passing through the polarizer, which is a great loss. Further, the service life of the panel is shortened under high luminance. Further, the thickness of the polarizer is about 0.2 mm, which does not meet the trend of thinning of OLED display panels.